1. Field of the Invention
The present invention relates to ureas, acylureas, and sulphonylureas corresponding to the general formula: ##STR3## in which A represents hydrogen or an R.sub.1 -- X group (in which X represents --CO or --SO.sub.2 and R.sub.1 represents an optionally substituted alkyl, cycloalkyl, aralkyl, alkoxy, aryl, aryloxy, etheroxy, aliphatic or aromatic group), R.sub.2 represents a hydrogen atom or an optionally substituted alkyl, cycloalkyl, aralkyl, or aryl group, and R.sub.3 represents a hydrogen atom or an alkyl group, particularly a tertiobutyl group.
The invention has as objects a process for the production of these compounds and also the new compounds which can be obtained with the aid of this process.
2. Description of the Prior Art
Various compounds are in fact known which correspond to the general formula (I) above, in which the symbols A, R.sub.2, and R.sub.3 have the meanings given, but which are not substituted in position 3 (R.sub.3 representing a hydrogen atom) or are monosubstituted in that position (R.sub.3 not representing hydrogen) or are disubstituted in that position (NH--R.sub.3 representing an ##STR4## group with R.sub.3 not representing hydrogen), and/or which, in position 1, are not substituted (A and R.sub.2 each representing hydrogen) or are monosubstituted (one of the two symbols A or R.sub.2 representing hydrogen).
However, no compounds disubstituted in position 1 and monosubstituted in position 3 are known. The process of the invention, as it will be defined hereinbelow, makes it possible not only to obtain in a general way the compounds of formula (I) above, but also to isolate the new compounds.
Various more or less effective processes have in fact been proposed for obtaining compounds of the formula: ##STR5## in which R.sub.1 -- X and R.sub.3 have the meanings given above for formula (I).
The processes most frequently used are the following:
1. Action of an isocyanate on a sulphonamide or an amide in a generally alkaline medium: EQU R.sub.1 -- X -- NH -- Na + O = C = N -- R.sub.3 .fwdarw.R.sub.2 -- X -- NH -- CO -- NH -- R.sub.3 PA1 2. action of an acyl or sulphonyl isocyanate on an amine: EQU R.sub.1 -- X -- N = CO + NH.sub.2 -- R.sub.3 .fwdarw. R.sub.1 -- X -- NH -- CONH -- R.sub.3 PA1 3. action of an aliphatic chlorocarbonate on a sulphonamide: ##STR6## b. Action of acyl or sulphonyl urethane thus obtained on an amine at high temperature: ##STR7##
These processes often give rise to a certain number of difficulties and do not always make it possible to obtain the expected result with a good yield.